👉 Infections are caused by microorganisms such as bacteria, viruses, fungi, and parasites that invade and multiply within a host's body, leading to illness. The history of understanding infections dates back to ancient civilizations, where people observed symptoms and attempted treatments without a scientific grasp of the underlying causes. However, significant progress began with the development of germ theory in the 19th century, primarily through the work of Louis Pasteur and Robert Koch, who identified specific microorganisms as the agents responsible for many diseases. This led to the creation of antiseptic techniques by Joseph Lister, reducing infection rates in surgeries. The discovery of antibiotics in the early 20th century, notably penicillin by Alexander Fleming, revolutionized infection treatment, making once-fatal diseases manageable. Public health measures, including vaccination programs and improved sanitation, further curtailed the spread of infections, transforming medical practice and significantly extending human lifespan. Today, advances in microbiology, immunology, and biotechnology continue to enhance our ability to diagnose, treat, and prevent infectious diseases.
